# # Check that firstmatch works with HASH # create table t1 (a int, b int); insert into t1 select seq, seq from seq_1_to_10; create table t2 (a int, b int); insert into t2 select A.seq,A.seq from seq_1_to_10 A, seq_1_to_10 B; set @save_join_cache_level=@@join_cache_level; set join_cache_level=6; explain select * from t1 where t1.a in (select t2.a from t2 where t1.b=t2.b); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 ALL NULL NULL NULL NULL 10 Using where 1 PRIMARY t2 hash_ALL NULL #hash#$hj 10 test.t1.a,test.t1.b 100 Using where; FirstMatch(t1); Using join buffer (flat, BNLH join) select * from t1 where t1.a in (select t2.a from t2 where t1.b=t2.b); a b 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10 10 set @@join_cache_level=@save_join_cache_level; drop table t1,t2; # # End of 11.0 tests #